Coking gas oven



L C. HAMLINK COKING GAS OVEN Oct. 11, 1932.

Filed April 28, 1927 5 Sheets-Sheet l L. C. HAMLINK COKING GAS OVEN Oct.11, 1932.

Filed April 28, 1927 5 Sheets-Sheet 2 F' RON 7' WASTE GAS l.. c. HAMLINK1,881,528

COKIN@ GAS OVEN Filed April 28, 192? 5 Sheets-Sheet 3 CMST//V @HAMM/ZnOct. 11, 1932.

NSE 11m m n,

Oct. 1l, 1932. l.. c. HAMLINK 1,881,528

COKIN@ GAS OVEN Filed April 28. 1927 5 sheets-Sheet 4 L. c. HAMLINK1,881,528

COKING GAS OVEN Filed April 28. 1927 5 sheets-Sheet 5 L L h .11,v

Oct. l1, 1932.

Patented Oct. 11, 1932 Unirse STA TESPATENT, ermee i LAZNBY C. AIJLENK,OF CLEVELAND HEGfI-ITS, OHIO, ASSIGNOR TO THE GAS V- CHNEZRY COVANY,'OFCLEVELAND, OHIOQA. CORPORATON OF OHIO COKIN@ GAS VOVEN Application1ed`Apri1 ,28,

My invention relates to coking gas-ovens and particularly to that classof apparatus in which a plurality of parallel retorts is employed, eachof the sides of which is associated with a heating unit for supplyingthe re- Ygases of combustion; together quired heat tothe coal in theretorts for maliing the desired gas product and ley-product coke whichheating units each includes regenerators for conserving the heat of thewith valve mechanisms for controlling the flow of the fuel-gas, the flowof the air for supporting the combustion of the latter and the flow ofthe gases of combustion', whereby the direc- :tion of flow of thelatterfthrough the units may be reversed and the heat of the regeneraitors applied to such air. Also in this type of apparatus, two waste-gasandtwo fuel-gas flues are employed, which, by means of vthe lvalvemechanism, are alternately rendered of au operative, the fuel-gas fluesor conduits being connected with a source of fuel-gas supply. rlhat is,the valve mechanism may be so manipulated that fuel-gas first passesthrough 29" 'one fuel-gas flue or conduit, then with air passes throughthe heating unit in one direction and is burned in v'such unit. ofcombustion then pass out through the one waste-gas ilue. Or the valvemechanism may be so manipulated as to cause the fuel-gas to i'irst passthrough the other fuel-gas flue or conduit, thenV with air through theheating unit in the opposite direction and burned in said unit, thegases of combustion then passing out through the other waste-gas flue.

Apparatus of this type is generally referred to as a by-product gas-ovensince comme 1cially usable gas is the product of main value and eolie isa by-product. Heretofore in apparatus of this type communication betweenthe fuel-gas flues and each heating unit has been controlled by twoseparate valves. There were, in consequence, twice as many of thesevalves as there were heating units and the element of expense was suchthat these valves had to be constructed from materials and in a mannersuch that they were not capable of withstanding a temperature of overapproXimately 7 O0o F. without injury.

The gases j 1927. Serial No. 187,243.

without first cooling the gas, inasmuch as'the ypreducer-gas would enterthe apparatus at a ytemperature of about 12000 F., or over, and rwouldeventually impair or destroy the controlling valves above referred to.Such cooling action, however, resulted in a loss of thermal etliciency,as will be understood by those skilled in the art, and required thepresence in the apparatus of a regenerator for reheating this gas inorder to produce the proper llgame temperature in the combustionchamers.

rllhe general object of the present invention is to increase theeiieiency of coking gasovens of the above-described type, one of the 'Yspecific objects being to provide a structure in which the producer-gassource may be connected directly with the apparatus, that is, withoutsubjecting the fuel-gas to a cooling operation before it passes into theheating units, and thereby enabling me to take advantage to the fullestextent possible of the economic value of the sensible heat in suchproducer-gas.

The said invention consists in character-g istics of structure andcombinations of parts hereinafter fully described and particularlypointed out in the claims.

In the annexed drawings:

Figure 1 represents a plan of a coking gasoven of the above-describedtype and embodying my invention.

Fig. 2 represents a front elevation.

Fig. 3 represents a vertical longitudinal broken section on an enlargedscale, taken upon the planes indicated by line IIL-III,

Fig. 1, and'viewed in the direction indicated by the arrows.

Fig. 4 represents a transverse section, on said enlarged scale taken uon the )lanes in- K dicated by line IV-IV, Fig. 3, and viewed in thedirection indicated by the arrows.

Fig. 5 represents a partial transverse section, on saidv enlarged scale,taken upon the plane indicated by line V-V,Fig.` 3, and

' viewed in the direction indicated by the dicatedby line X-X, Fig. 2,viewed in the direction indicated by the arrows.

Fig. 11 represents a transverse verticalsection otsaid valve mechanismtaken upon the` plane indicated by line XlmXl, Fig. 1.

Fig. 12 represents a transverse vertical section taken upon the planeindicated by line XII-XIF Fig. 1, and

13 represents a longitudinal vertical section taken upon the planeindicated by line XIII-XIII, l 1.

In the illustrated embodiment of my i ivention, suitable materials suchas briclr, masonry andl steel are employed to form a main batterystructure 1, emboc a plurality of' parallel and verticall oven chambers2 extendingv transversely of the structure 1, as shown in Fi 3, eachprovided the top with suitable charging openings 3 and covers 4therefor, andv an oven-gas outlet 5, Fig. 5, all of these outlets beingconnected to a main takeoif duct 6, for conducting the oven-gas to asuitable gas-holder (not shown) as will be understood.

ln this` main stru ture is also provided a plurality of heating unitsfor heating the two opposite sides ot the oven chambers.`

of these units includes a combustion i. fr 7 and these cb aro-bersalternate longitudinally of the battery, with the oven chambers 2, sothat each side of each oven chamber is laterally adjacent to acombustion chamber 7 as shown in Fig. 3.

Each Ycombustion chamber is sub-divided into a plurality ot verticalfront heating coni- `vbustion flues 8, and rear heating ilues 3 byvertical walls 82 terminating short of the top of the oven chamber toform a horizontal passagevQ, Figs. 3 and 4;

Beneaththe front part of each combustion chamber and parallel therewithare two Ypassages and 11, and beneath the rear part i Y The bottom ofeach vertical heating` flue S and18 is provided with an opening 15 or154 which communicates with two laterally di- 4verging passages orports, 16 and 1701916.

and 17", whose lower ends respectively com- Vmunicate with the passages10 and 11, and

10 and 11', 3, 4, and 6. The latter passages are each formed at theirsides with ledges 18 and 13, respectively, upon which rest looselyplaced damper-bricls 19 and 19, Fig 8, which may be used to vary theextent 01" communication of the passages 16 and 17 and 16 and 17 withthe passages 10, 11, 10 and 11 by slidingthem along the ledges 18 and13, to partially'cover the bottoms of said passages 16 and 17 and 16"and 17 Beneath each combustion chamber 7 are two transversely alinedvertical regenerators 20and 20 whose inner ends are separated by alongitudinal wall 21, Figs. 3 and 6, and adV jacent thereto and parallelwith these regenerators are two narrow vertical fuel-gas passages 22 and22" respectively, and also alinevd transversely of, the main batterystructure,

Figs; 3., 4 and 9.

lFliese fuel-eas assaoes 22 and 22 are ro.-

vided internally with staybricls 23 for sup-V porting their Walls, asshown in Figs. 3 and 4, and their inner ends are separated from eachother by the wall 21. 'Y

The upper end of each front regeneratoi Y 2O is connected with a passage1l by means of a plurality of vertical passages 24,. correspending innumber with the heating lues 3 which are located above the reoeneratorsy20, Fig. 6; and each of the front fuel-gas passages 22 is, connectedwith a passage 10, by the saine number oi vertical passages 25, Fig. 4.Similarly the upper end of each rear regenerator 20 is connected with apassagev 11 by means of ai plurality oi' vertical passages 24, coresponding .in number with ythe heating lues 3 which arelocated above thenregenerators 20', and each of therear fuel-- Ygas passages 22 isconnected with a passagel 10 by the saineV number of vertical passages25". The bottoni ont each of the front regenerators 2O is connected withva common longitudinally extending horizontal waste-gas Hue 26 by meansof a vertical passage 27, and the bottom of each of the rearregenerators 20 with a common longitudinally extending horizontalwaste-gas flue 28 by means of a vertical passage 29, as shown in Figs. 3and 6. The degree of vcommunication between the regenerators andthewaste-gas flues 26 and cating with both of the regenerators and 28l maybe controlledby .slidable dampergitudinally extending horizontalfuel-gas flue 31 by means of a vertical passage 32, andthe bottom ofeach rear fuel-gas passage 22" is connected with av commonlongitudinally extending horizontal fuel-gas flue 33 4by 'means of avertical passage 34, asshown in Fig. 4. The degree ofcommunicationbetween the fuel-gas passages 22 and 22 andthe fuelgas iues31 and 33 may be controlled by slidable damper-bricks 35, Figs. 4 and 9.

Below each regenerator and 20 is a horizontal air-supply passage 36or'36 whose communication with vvthe atmosphere is controlled by adamper 37 or 37 Fig. 6. As has been common practice heretofore, suitablemeans are provided for simultaneously actuating all of the front dampers37, and

aoV

similar means for simultaneously actuating all of the rear dampers 37',and which it will hence not be necessaryV to further describe.

AccessA to the damper-bricks controlling communication between theregenerators 20 and 20 and the waste-gas flues 26 and 28 is affordedthrough the outer ends of the air-passages 36 and 36 and to thedamper-bricks controlling communication between the fuel-gas passages 22and 22 and the fuel-gas flues 31 and 33 through the outer openings 38and 38 normally closed by doors 39.

Each heating unit therefore consists of two transversely alined verticalregenerators', two transversely alined vertical fuel-gas passagesrespectively adjacent the regenerators,

a combustion chamber above and communifuel-gas passages, thecommunication between the regeneratorsand combustion chambers beingcontrollable and the communication between the fuel-gas passages andcombustion chambers being likewise controllable.

These heating units also include the air-supply passages 36 and 36 forthe regenerators 20 and 20, respectively.

It will be noted from the description and drawings that the directcommunication between the fuel-gas flues 31 and 33 and the heating unitsis permanently open as is also the communication between the said units`and the waste-gas flues 26 and 28, the amount of` opening beingcontrollablevby the damperbricks 35 and 30, respectively as describedabove.

Each of the fuel-gas flues 31 and 33 is j closed at oneuend of the mainbattery structure as shown in Fig. 1 at 31a and 33a, and extends beyondthe other end of said' structure, the left-hand end thereof Vasillustrated, and access to these latter extending ends is controlled bya reversing valve 40.0f any -my present invention and I have illustratedsuch a valve as applied to my improved apparatus, in the drawings, Fig.1, 2, 10,-11,.12 and 13. Y

The left-hand extending ends of the said two fuel-gas iiues terminateunder the casing 41 of thevalve 40, Figs. 1 and 12, and communicate withthe interior of said casing through vertical passages 31 and 33respectively, and the top of such casing is connected-with a downcomerpipe 42 which in turn is connected with a Y gas-producer 44 whichsupplies hot fuel-gas. A dust-catcher 43 may be interposed between thegas-producer and downcomer pipe.

Between the end portions ofthe tw'o fuelgas ues 31 and 33 is anauxiliary waste-gas flue 45 which communicates with the interior o f thecasing of the valve by means of a vertical passage and thiscommunication is controlled by a slide-valve 46, Figs. 12 and 13.

The other end of this flue 45 communicates with the stack 47, Fig. 1.

The valve 40 is provided with the movable member 48, Figure 12, whichmay be shifted to permit communication between the downcomer 42 andeither the fuel-gasV iue 31 or the fuel-gas flue 33. In so doingcommunication is established between the auxiliary flue 45 and thatfuel-gas flue which is shut off from communication with the downcomer42.

Each of the waste-gas flues 26 and 28 is closed at one end of the mainbattery structure as shown at 26a and 28a, Fig. 1, and

extends beyond the other end of saidV structure, the left-hand endthereof as illustrated.

rl`he extending ends of the two waste-gas flues 26 and 28 terminateunder the casing 50, Figure 11, of a valve 49 similar to valve 40, andcommunicate with the interior of said casing through vertical passages26 and 28 respectively. The auxiliary waste-gas flue 45 extends twowaste-gas flues, Figs. 1 and 11, and communicates with the interior ofthe casing 50 of reversing valve 49 by means of the vertical passage45a.

The movable valve-member 51 of the valve 49., may be shifted so as toestablish communication between the auxiliary waste-gas passage 45 andeither one of the waste-gas iiues 26 and 28 to the exclusion of theother, as will Vbe understood.

Descriptz'zmA of operation,

between the end portions of the lines in Figs. ll and 12, respectively.Under such conditions the rear air-control danipers 37 are given theiropen position and the front air-control dampers 37,v given their closedposition, as shown in Fig. 6.y

Let it also be assumed that the apparatus. has been in previousoperation in a inan-V l sages 34 and into and through the rearfuelgaspassages 22. Frein the latter itipasses up throughthe passages 25to the transverse passages thence to the passages 16 and into the rearheating flues 8 which are above 1 the rear regenerators` 20 andfuel-gasY pas-V 28 sages 22. Y s Y Simultaneously with theabove-described direction of travel of the fuelgas, air passes Y intothe rear air-passages 36 up through the heated rear regenerators outthrough the passages 24 and into the transverse passages 11. F rom thelatter the heated air passes up through the passages 17 into the rearheating flues 8 into which the fuel-gas is passing. The air and oastherefore become mixed in these heatino' fines 8 and combustion of the DY i gas is effected therein.

The frases of heatin@` dass out of the rear combustion lues into thepassages?) ano over to the heating flucs which are above the" front bregenerators 20. Y

As' Will be noted from Fig. ll, the front waste-gas flue 26 is connectedwith the auX- '1" Lf i45 lh 'thtle iiiaiy waste gas uo ant ence wi i Lestack. It will also be noted from Fig. 12 th at the front fuel-gas flue3l is connected with the said auxiliary flue 45, but this connection islimited by the slide-valve 46, the latter being set so as to materiallyrestrict the draft from the fuel-gas flue 3l 'to the stack. Y

The greater portion of the gases ofY coinbustion, therefore, pass fromthe front coinbustion chambers down through the passages 1'4" connectedtherewith, through passages 24 and into and through the frontregenerators 20, heating thelater. From the regenerators V20, they then.pass through the passages 27 connectel therewith, into the frontwastegas flues 26, into valve-member 51, over into the waste-gas fine 45to the'st'ach. V f

A much smaller quantity of these gases and which is regulatable by theslide-valveV 46, passesL from the front heating flues'S, down throughthe passages i6 connected therewith throughV assao'es 25 intoandithrough the front fuel-gas passages 22, through ythe passages 32, intoand through the front fuel-gas flue 3l, into valvelchainber 48, and pastthe valve 46, through passage 45 (Fior. 13) toauxiliary Waste-gas flue45 and thence tol the stack, thuspurging the front fuel-gas passages' 22and the front fuelgas fiile 31'of any air which might khave gainedaccess thereto by leakage or otherwise, and so preventing theformationof an explosivefinixtur'e when the operation is reversed ashereinafter describe Y To reverse'the above-'described operati-on,AV thevalves 40 and 49 are operatedto shift their movable members over toVtheir other positions, rear air dampers 37 are closed and front airdampers 37 vare opened.V Valve 40 will vthen establish connectionbetween the downconier 42 and the front fuel-gas flue 3l and alsoestablishconnection between 'the flue 45 (and hence the stack) and therear fuel-gas `iue 33'.` Valve 49 willthen establish` connection betweenthe flue 45 (and' hence the stack)V and the rear waste-gas fine quenceflow into the vfront fuel-gas flue 31',

up through-the front fuel-gas and into the front heating flues 8.

Air will flow yinto the front air-supply passages 36 up through theheated front regenerators 20 and into the front heatingrflues 8 where itsupports Vthe combustion of the fuel-gas. The gases of combustion passup to and through passages 9'and down ythe-rear heating flues 8. The'greater part of-these' gases then passes through passages 17', thenpasses through and heats the rear regenerators 20, then passes into andthrough'the rear Waste gas fine 28, through valve 49 to the stack.`A'sinaller amountof the gases passes through passagesl and purges therear fuelV gas passages 22" and the rear fuel gas flue 33, as a resultof the connection of the rear fuel-gaslue with the stack by the valve40,`

aswill be understood.

It willv be noted from the above const-rnc! tioii,'that by providingvalve mechanism for controlling the influx of fuel-gas into the fuel-gasflues 3l and 33and for controlling the efflux of the gases of combustionfromv the waste-gas fines 26 and 28, all of theV direct connectionsbetween the fuel-gas fines and heatingunits, and betweeny the heatingunits and the wastegas fines may be left perinanently open, after beingset `as desired byf means of the damper-bricks 35 andV 30,-respeotively, thus eliminating theV necessity of providing separatevalves,` for controlling ac-V cess to and discharge from said units. Avalve-mechanism for complete control Vand. capable of eeoting the'necessary reversal', is therefore provided, which is greatly simpliliedjas compared with the previous practice, andlwhich may therefore; bemade heat- Yresisting to any required degree without passages 22 ioo iis

ist

mamas wise, and Yenter the Vfuel-gas passages and combustion chambersata high degree of temperature, usually-about 1300O F. Y

It will also be Seencfrom the above-described construction that thedamper-bricks l9and 19vby being 4placed intermediately of the bottom ofthe combustion chambers and tops of the fuel gas passages 2:2, Q2 andthe regenerators 20 -'and 2l are out of the direct influence of thedestructive action of the high heat generated in the combustion chambersduring combustion, thus tending to prolong the life of these bricks andare also in a position in whichfthey are readily accessible foradjustment. f Y

`.By eliminating the multiplicity of controlling'valves heretoforeemployed and as heretofore described, both the fuel-gas liuesand'waste-gas iiues may be placed beneath the apparatus, andincorporated in the masonryffundation structure as shown.

It will be further'noted that inasmuch as the fuel-gas need not bereheated, a regenerator for heating such gas is not required. This makeit possible to make the fuel-gas passages 22 and22 vnarrow and theregenerators 20. and 20 wide, as shown in Figure 3, thus providing agreater regenerator surface for the airL than has heretofore beenpossible in by-product gas ovens using producer-gas as fuel. At the sametime, the total regenerator surface is reduced ascompared to thatheretofore required,`thus resulting in economy of construction.

What claim is:

l. In a coke oven battery, a series of alternate coking chambers andcombustion chambers for heating the same arranged side by side in a row,a regenerator unit below each of said combustionchambers, eachof theregenerator-units comprising two regenerators and each of theregenerators of each of said units communicating with the combustionchamber above the unit, two fuel-gas flues extending along said batteryand communieating with eachof said combustion chambers and an air inletfor each ofsaid regenerators and means for controlling same; a singlereversing valve for controlling lall of the fuel-gas flow into both ofsaid fuel-gas flues; two waste-gas lues extending along said battery,the one communicating with one of the regenerators of each of said unitsand the other waste-gas flue with the .other regenerator of the sameunit; vand means for controllingthe out-flow from said waste-gas iues.

2. A coke oven battery comprising a series of alternate coking chambersand combustion chambersfor heating the coking chambersarranged side byside in a row; a regenerator unit associated with each combustionchamber, each regenerator unit including two regenerators each ofwhichhas communication with its associated combustion chamber and eachregenerator having an air inlet means for-controlling the air inlets;two fuel conduits` extending lalong the battery and havingcommunication with all the combustion chambers; two waste-gas fluesextending along said battery and communicat-A c ing with the regeneratorunits; an outlet flue for waste gases adapted to communicate with saidwaste-gas flues a single reversing valve associated with thefuelconduits andv adapted to control the flow of fuel from a source ofsupply alternately through said conduits to all the combustion chambers;and valve mechanism associated with the waste-gas iues and adapted tocontrol the flow of wastegas from' said two waste-gasflues to the outyling the air inlets; a waste-gas flue system including two waste-gasflues extending along the battery, one of said flues communicating withthe front regenerators and the second flue communicating with the rearregenerators, 4an outlet-Hue adapted to communi.- cate with said`waste-gas flue, and asingle reversing valve associated with said fiuesand adapted to place said waste-gas fines alternately in communicationwith the out-let flue and a fuel-gas conduit system including twoconduits extending along the battery, one conduit having communicationwith the front portions of the combustion chambers and thesecond conduithaving communication with the rear portions of the combustion chambers,and means associated with said conduits and adapted to control the Howof fuel Igas through the conduits to the combustion chambers. y

4. A coke oven battery comprising a series of alternate coking chambersand combustion chambers for heating the same arranged side by side in arow; a regenerator unit below each of said combustion chambers, each ofthe regenerator units comprising two regenerators each of whichcommunicates with the co-mbustion chamber above the unit; an

air inlet for each of said regenerators; means for controlling the airinlets; two vfuel-gas conduits extending along said battery andcommunicating with each of said combustion chambers; a single reversingvalve for con-- trolling the fuel-gas iow alternately into said fuel-gasconduits; two waste-gas ilues extending along` said battery and.communicating with the two regenerators of each of ioo lee

6 'reagisce i heating units including combustion chambers, a frontvseries and a rear series of regenerators communicating with spacedportions lof the combustion chambers and hav-` ing valved air inlets,and the coking and combustion chambers being disposed side by side inL arow and in alternate relation to each other; a gas flue systemcomprising two waste-gas flues extending along the battery, one fluecommunicating with the front series of regenerators and the second fluecommunicating with the rear series of regenerators, an outlet-flueadapted to communicate with said waste-gas flues, a reversing valveadapted to place said two waste-gas flues in communication with saidoutlet-flue, two fuel-gas conduits extending along the battery, one ofsaid conduits having communication with one portion of each combustionchamber and the second conduit having communication-with j f anotherportion of each combustion chamber,

a valve associated with. said conduits, and a passage extending from thelast-mentioned Valve to the outlet-flue, said last-mentioned valve being`adapted to connect one of the fuel-gas conduits-with a source offuel-gas and to connect the other conduit with said passage. Y

6. A coke oven battery comprising a series of alternate coking chambersand combust. tion chambers for heating the same arranged side by side ina row; a regenerator unit belowe'ach combustion chamber, said unitincluding a front regenerator communicating with the Vfront portion ofthe combustion chamber directly above and a rear regenera-torcommunicating with the rear portion of the same combustion chamber;valved air inlets for said regenerators; a waste-gas flue systemincluding two waste-gas iues extending along the battery,.one fluecommunicating with all the front regenerators and the second Huecommunicating with all the rear regenerators, an outlet-flue adapted tocommunicate with said waste-gas flues, anda reu versing valve interposedbetween the two waste-gas fines and the outlet-flue and adapted to placeeither of said two waste-gas flues in communication with the outlet-nue;and a fuel-gas conduit system including two fuelgas conduits 4extendingalong the battery,

one conduit having communication with the front Vport-ion of eachcombustion chamber and the second conduithaving communication with therear portion of each combustion chamber, and a valve mechanism'associ-65- ated with said conduits and communicating duits with a source-0ffuel-gas and the otherf conduit with the outlet-flue.

7 In a coke oven battery, a series of col;- ing units each comprising acoking chamber and a combustion chamber side by side vfor heating thesame, said units being positioned in a row so that thecoking chambersalter-V nate with the combustion chambers; a series of auxiliary unitsbelow the coking units, each auxiliary unit corresponding to acokingunit and including two regenerators and a fuel passage adjacent thereto,each regenerator being substantially wider than .the fuel passageadjacent thereto, and the width of each auxiliary unit beingsubstantially the same as the width. of the corresponding coking unit.;conduits connecting each combustion chamber to the two regenerators andthe fuel passage of the corresponding auxiliary unit; two fuel conduitsextending along the battery, some ofthe fuel passages communicating withone of said fuel conduits and the balance of the fuel passagescommunicating with the other fuel conduit; and a Vsingle reversing valvefor controlling the flow of fuel through said fuel conduits to all ofthe fuel'passages.

8. A coke ovenrbattery comprising a series of colring units positionedside by side.

in a row, eachV coking unit consisting of a coking chamber and acombustion chamber contacting therewith and the units being'po; sitionedso that the coking chambers alternate withthe combustion chambers; aseries of auxiliary units positioned side Yby side in a row below thefront portions of the coking units, each auxiliary unitbeing operativelyassociated with one of the combustion chambers and including aregenerator and a fuel-gas passage adjacent thereto, each regeneratorbeing substantially wider than the fuel-gas passage adjacent thereto andthe combined width of one regenerator and its adjacent fuel-gas passagebeing substantially the same as the combined width of' the correspondingcoking and combustion chambers associated therewith; a second series ofsimilar auxiliary units similarly positioned below the rear portions ofthe 'coking units; air inlets for the regenerators; means forcontrolling the Viniiow of air through said inlets; a wastegas iuesystem including two waste-gas iues extending along the auxiliary units,one flue communicating with the regenerators of one series of auxiliaryunits and the second flue communicating with the regenerators of theother series of auxiliary units, an outlet-flue adapted to communicate-with said wastegas flues, and a reversing Valve adapted to place thetwo waste-gas flues alternately in communication with the outlet-flue;and a fuel-gas feeding system including two fueliro gas conduitsextending along the auxiliary units, one conduit communicating with theueLgas passages of one series of auxiliary units and the second conduitco1n1nunicating with the fuel-gas passages of the other

